/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 2001-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: VariableRefBase.java,v 1.5 2005/09/28 13:48:18 pvedula Exp $
 */

package com.sun.org.apache.xalan.internal.xsltc.compiler;

import com.sun.org.apache.xalan.internal.xsltc.compiler.util.Type;
import com.sun.org.apache.xalan.internal.xsltc.compiler.util.TypeCheckError;
import java.util.Objects;

/**
 * @author Morten Jorgensen
 * @author Santiago Pericas-Geertsen
 */
class VariableRefBase extends Expression {

  /**
   * A reference to the associated variable.
   */
  protected VariableBase _variable;

  /**
   * A reference to the enclosing expression/instruction for which a
   * closure is needed (Predicate, Number or Sort).
   */
  protected Closure _closure = null;

  public VariableRefBase(VariableBase variable) {
    _variable = variable;
    variable.addReference(this);
  }

  public VariableRefBase() {
    _variable = null;
  }

  /**
   * Returns a reference to the associated variable
   */
  public VariableBase getVariable() {
    return _variable;
  }

  /**
   * If this variable reference is in a top-level element like
   * another variable, param or key, add a dependency between
   * that top-level element and the referenced variable. For
   * example,
   *
   * <xsl:variable name="x" .../>
   * <xsl:variable name="y" select="$x + 1"/>
   *
   * and assuming this class represents "$x", add a reference
   * between variable y and variable x.
   */
  public void addParentDependency() {
    SyntaxTreeNode node = this;
    while (node != null && node instanceof TopLevelElement == false) {
      node = node.getParent();
    }

    TopLevelElement parent = (TopLevelElement) node;
    if (parent != null) {
      VariableBase var = _variable;
      if (_variable._ignore) {
        if (_variable instanceof Variable) {
          var = parent.getSymbolTable()
              .lookupVariable(_variable._name);
        } else if (_variable instanceof Param) {
          var = parent.getSymbolTable().lookupParam(_variable._name);
        }
      }

      parent.addDependency(var);
    }
  }

  /**
   * Two variable references are deemed equal if they refer to the
   * same variable.
   */
  @Override
  public boolean equals(Object obj) {
    return obj == this || (obj instanceof VariableRefBase)
        && (_variable == ((VariableRefBase) obj)._variable);
  }

  @Override
  public int hashCode() {
    return Objects.hashCode(this._variable);
  }

  /**
   * Returns a string representation of this variable reference on the
   * format 'variable-ref(<var-name>)'.
   *
   * @return Variable reference description
   */
  @Override
  public String toString() {
    return "variable-ref(" + _variable.getName() + '/' + _variable.getType() + ')';
  }

  @Override
  public Type typeCheck(SymbolTable stable)
      throws TypeCheckError {
    // Returned cached type if available
    if (_type != null) {
      return _type;
    }

    // Find nearest closure to add a variable reference
    if (_variable.isLocal()) {
      SyntaxTreeNode node = getParent();
      do {
        if (node instanceof Closure) {
          _closure = (Closure) node;
          break;
        }
        if (node instanceof TopLevelElement) {
          break;      // way up in the tree
        }
        node = node.getParent();
      } while (node != null);

      if (_closure != null) {
        _closure.addVariable(this);
      }
    }

    // Attempt to get the cached variable type
    _type = _variable.getType();

    // If that does not work we must force a type-check (this is normally
    // only needed for globals in included/imported stylesheets
    if (_type == null) {
      _variable.typeCheck(stable);
      _type = _variable.getType();
    }

    // If in a top-level element, create dependency to the referenced var
    addParentDependency();

    // Return the type of the referenced variable
    return _type;
  }

}
